Ōya stone

Ōya stone is an igneous rock, created from lava and ash. Ōya stone was famously used in the facing of Frank [Lloyd Wright]'s Imperial Hotel in Tokyo. One reason this stone was used is because it has a warm texture and is easily carved, which allows much versatility. Ōya stone can have different colors and is also fireproof.
Ōya stone can only be found in an area 4 kilometers to the east and west by 6 kilometers to the north and south around the town of Ōya, near Utsunomiya, but there are reserves of around 600 million tons.